1. Field of the Invention
The present invention relates to disc players for writing information in a disc such as a compact disc (CD) or a digital versatile disc (DVD) and/or for reading information written therein. Further, the preferred embodiments of the present invention relate to a disc-positioning mechanism for positioning an inserted disc with respect to a turntable.
2. Description of the Related Art
Car-mounted disc players typically have a drive chassis having a photo pickup, a turntable, and an arm clamp that is operable to move up and down such that a disc is chucked (clamped) by the turntable and a clamper rotatably supported on the arm clamp. Although the arm clamp is urged so as to come close to the drive chassis, during ejection (in a standby state) in which the disc is not loaded on the disc player or during transfer of the disc, the arm clamp remains above the drive chassis in order to hold the clamper in a position away from the turntable. Meanwhile, when the disc is transferred to a playing position, the arm clamp moves down in order to come close to the drive chassis, and the disc is then chucked by the clamper and the turntable. The drive chassis has a disc-positioning mechanism disposed thereon, and the disc transferred to the playing position is properly positioned with respect to the turntable by the disc-positioning mechanism. In such a car-mounted disc player, either of small and large discs having diameters of, for example, 8 cm and 12 cm is inserted for reading and/or writing information. Therefore, the disc-positioning mechanism is required to position both discs having different diameters from each other with respect to the turntable.
Such a known disc-positioning mechanism has a structure in which the arm clamp has a pair of positioning members movably supported thereon, each having a pin disposed thereon in a hanging manner and protruding in a transfer route of the disc. In such a disc-positioning mechanism having the above-described structure, when a small disc is inserted in the disc player, the outer periphery of the disc abuts against the pins remaining at respective predetermined positions so that the disc is positioned with respect to the turntable. When a large disc is inserted in the disc player, the outer periphery of the disc abuts against the pair of pins while the disc is being transferred to the playing position, and then the positioning members move together with the disc. Thus, when the large disc reaches the playing position, the positioning members having the respective pins come to a halt, whereby the center of the large disc is properly positioned with respect to the turntable.
However, in the foregoing known the disc-positioning mechanism, when an external vibration, shock, or the like is exerted on the disc player during transfer of the disc, sometimes the disc which is being transferred to the playing position does not abut against the pins and hence passes over below the pins, thereby causing the positioning members not to work properly and resulting in a chucking failure of the disc. Likewise, such a problem occurs when the positioning members are provided on the drive chassis side. In this case, a vibration or other disruption may cause the disc to pass over above the pins, resulting in a chucking failure.